[css-counter-styles] Invalid @counter-style should just not define a counter style, not be ignored #1682
Description
In #1133, we just decided that an @font-face rule without its minimum required descriptors should be treated as valid (so it shows up in the OM), but just doesn't define a font face for the document.
We should be consistent in applying this decision, which means that an @counter-style rule without its minimum required descriptors (system and either symbols or additive-symbols) is valid, but does not create a counter style for the document.